LY 294002 is a potent inhibitor of phosphoinositide 3-kinases (PI3Ks). Two of these are the proto-oncogene serine/threonine-protein kinase (PIM1) and the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma isoform. With an IC50 of 1.4µM it is somewhat less potent than wortmannin, another well-known PI3 kinase inhibitor. However, LY294002 is a reversible inhibitor of PI3K whereas wortmannin acts irreversibly. Application of LY294002 causes a substantial acceleration of MEPP frequency (150 μM) at the frog neuromuscular junction through a mechanism that is independent of intraterminal calcium. LY294002 causes the release of MEPPs through a perturbation of synaptotagmin function. [1][2]